Toxoplasma gondii protects from IgE sensitization and induces Th1/Th2 immune profile.

Toxoplasma gondii (T gondii) infection has been associated with protection against allergy and autoimmune diseases. We investigated the effects of T gondii infection on cytokine and antibody responses in atopic and nonatopic Brazilian subjects. We have measured in whole‐blood cultures, Th1 (IFN‐γ and IL‐12), Th2 (IL‐5) and regulatory cytokine IL‐10 in blood cells unstimulated and stimulated with pokeweed mitogen or T gondii soluble tachyzoites antigen (STAg) or Dermatophagoides pteronyssinus antigen. A significant negative association was found between high levels of anti‐dust mite IgE and T gondii seropositivity (OR = 0.46; 95%CI = 0.25‐0.85). STAg stimulation induced a mixed profile of Th1 and Th2 cytokines (IFN‐γ, IL‐12 and IL‐5) in Tg‐positive atopic individuals compared with Tg‐negative atopic individuals (P <.0001, P =.033 and P =.003, respectively). In contrast, IL‐10 production was not different between these groups. No association was found between T gondii infection and asthma. We hypothesized that the protective effect on atopy might be related to the strong Th1 immune response to T gondii found on the seropositive subjects. From our knowledge, this is the first study to investigate the association between atopy and T gondii infection in Brazilian subjects, analysing the cellular immune responses. [ABSTRACT FROM AUTHOR]